Thursday, March 12, 2015

Two weeks ago I wrote about a book – Catching Fire by Richard Wrangham – which postulated
that the discovery of cooking greatly improved the food success of the hominid
species and led to the evolutionary change that produced us. Many side issues arise as a result of this premise. A very important one
is that pairing of males and females may have been driven by a need to protect
cooked food rather than primarily for sexual or reproductive reasons; another
was that this led to the male domination of women.

The issue that seemed to raise the most interest was how
this relates to the issue of obesity in the modern first world. Caro pointed
out some scary statistics. Wrangham notes that at the start of the 21st
century, 61% of Americans were “overweight enough to begin experiencing health
problems as a direct result.” He notes that
fifty years after the observation was first made, more people in the US die
from too much food rather than too little. Diet conscious people wonder around the supermarket reading calorific values on food packages.

I don’t pretend to have any expertise whatsoever in this
area, but Wrangham makes some points and observations that seem at least plausible. In his book's epilogue – titled The
Well-Informed Cook – he discusses the way in which food value is measured,
which, in broad brush-stroke terms, goes back to Atwater’s meticulous and
pioneering work in the nineteenth century.
Sparing you the details, he found that food could roughly be divided
into three components – proteins, fats, and carbohydrates – and that within
these components the available energy was fairly uniform. He also estimated how much of the food
material was absorbed by the body. So a mass/energy balance tells you how much energy is available from each food
group. Nice and simple and basically the
way in which foods are labelled and treated to this day.

Wrangham points out two major flaws in this. Firstly, it
doesn’t take into account how much energy it requires to digest the foods. Thus
highly processed, soft, cooked foods are rapidly and easily broken down by the
digestive enzymes and take little energy to absorb. Conversely, rough-milled and raw foods are
much more difficult to digest, and while the body works hard at doing so, much
more energy is used in the process. Thus
the same amount of calories in different forms leads to a substantially
different net gain. Protein costs more
to digest than carbohydrates and fats have the lowest digestive cost of the
three. A study in 1987 showed that people on a high fat diet achieved the same
weight gain as people eating around five
times that number of calories in carbohydrates. This suggests that the
Atwood system is far too simple to be useful in the modern environment, yet it
is still the basis for food labeling.

The second related issue with the system is that the state
of the food – liquid, soft cooked solid, meat, raw food – makes a large
difference to the cost of digestion. The latter items lead to a much higher
excretion rate, which Atwood had assumed to be essentially constant at around
10%. Detailed data on this is hard to obtain for multiple forms of multiple foods
and so it is expressed only in qualitative terms like “eat less processed foods,” “roughage
is good for you,” “eat fresh salads.” None of this is really helpful, and certainly
doesn’t appear in the nutritional food labels. What you see is what you get,
but it isn’t very meaningful.

Richard Wrangham with non-cooking friend

This is how Richard Wrangham concludes his discussion:

“The human ancestral environment was full of uniform
problems: how to get fuel, how to regulate feeding competition, how to organize
society around fires. The big problem of diet was once how to get enough cooked
food, just as it still is for millions of people around the world. But for
those lucky enough to live with plenty, the challenge has changed. We must find
ways to make our ancient dependence on cooked foods healthier.”

If Wrangham is right, we now need to avoid the very foods we
have evolved to seek. The problem is
that those are therefore exactly the ones we like.

8 comments:

Fascinating! I've recently had to become more aware of my diet, for health reasons unrelated to weight alone, and all of the things you're saying resonate strongly with me on multiple levels. Great post!

All too believable, Michael! Fortunately (for me) I'm still in the 39% without significant weight issues.

Enjoying LCC, went to two great panels and the interview with Phillip Margolin, who was very entertaining and informative. Tomorrow is several more panels, lunch with Tim and Lisa, and Tim's interview. I'll try to take some pictures for those unfortunates unable to attend...

As you're enjoying yourself EvKa at LCC and flaunting that good time to we "unfortunates" think of AA and me having dinner together tomorrow night consuming all the foods Michael has warned us off of. SO THERE. And please give Tim a hug for me. Lisa a bit more...as in a beer.

EvKa, You have heard by now that I got a phone call literally while I was zipping up my luggage. It stopped me in my tracks. I am glad I stayed home because I got to see my husband through a bit of a crisis. But I am sorry that I did not get to attend the conference. American Airlines told me that I can use my ticket anytime in the next year without penalty, so I may yet show up in Portland.

I wish I was there with you all, but I am stuck at Glasgow airport trying not to be stuck at Glasgow airport.Alcohol is the best muscle relaxant in the world, so you can really raise a glass to your own good health. And if you drop a strawberry into the Champers, that's one of your 'five a day'!